1 Thessalonians 5:3

When they are saying, Peace and safety, then sudden destruction cometh upon them, as travail upon a woman with child; and they shall in no wise escape.

When they are saying ... has the equivalent meaning of "When people are saying."[8] Primarily, it is the non-Christian portion of humanity in view, because the thrust of this warning is that Christians may not find themselves surprised by the Lord's coming. As Moffatt expressed it:

While the Day comes suddenly to Christians and unbelievers alike, only the latter are surprised by it. Christians are on the alert, open-eyed; they do not know when it is to come, but they are alive to any signs of its coming.[9]

Peace and safety ... At the precise moment when humanity feels most secure in their rebellious and sinful course against God, and at a time when all of the devices of government and society may have produced the environment in which man may fancy that the peace, prosperity and safety of the whole world have been secured - precisely then shall the Lord descend from heaven with a mighty shout, the voice of the archangel and the trump of God!

Travail upon a woman with child ... A very apt simile is this; for, as Ward noted, "The sudden pain of labor, even when it is expected (and a woman expects labor just as a Christian expects the [@parousia]), it is sudden when it comes."[10]

[8] J. R. Dummelow, Commentary on the Holy Bible (New York: The Macmillan Company, 1937), p. 979.

[9] James Moffatt, The Expositor's Greek Testament, Vol. 4 (Grand Rapids, Michigan: Wm. B. Eerdmans Publishing Company, 1967), p. 39.

[10] Ronald A. Ward, Commentary on 1,2Thessalonians (Waco, Texas: Word Books, Publisher, 1973), p. 110.